<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta http-equiv="X-UA-Compatible" content="ie=edge">
  <title>index</title>
  <style>
    html,body {
      height: 100%;
      width: 100%;
      margin: 0;
      padding: 0;
      overflow: hidden;
      background-color: black;
    }
    body{
      display: flex;
      justify-content: center; /* 水平居中 */
      align-items: center; /* 垂直居中 */
    }
  </style>
</head>
<body>
  <button>
    <a href="./china.html">中国地图</a>
  </button>
</body>

  <script>
  </script>
</html>